Hydrodynamic components for use in starting units, retarder units or gearing assemblies may be switchable, and these components may be filled and emptied. Rapid chilling may be required. For example, when hydrodynamic constructional units form hydrodynamic retarders, very short filling times may be required for safety to achieve a rapid braking action or a regulated torque profile that, for example, may cause a certain speed profile when starting an engine. According to general designs known in the prior art, the filling occurs with the aid of operating material reservoir devices, which use external auxiliary power from the vehicle or from their own force to accelerate the filling process when hydrodynamic elements are being filled. In this case, piston-type reservoirs, which are actuated by spring force or compressed air from the compressed air system of the vehicle, may be used. The entire housing space may be set under pressure, which causes operating material to exit the oil sump into the corresponding, hydrodynamic component. Corresponding pump devices may also be employed to aid filling.
However, it is believed that the designs according to the prior art disadvantageously consume power with respect to the conversion and presupposing of special equipment.